#include<cstdio>
#include<cmath>
int main()
{
	printf("%f\n",atan2(1,1));
	printf("%f\n",atan2(1,-1));
	printf("%f\n",atan2(-1,-1)+2*acos(-1.0));
	printf("%f\n",atan2(-1,1)+2*acos(-1.0));

	return 0;
}
